Interesting spinning on the Sinai airplane crash. A bomb seems to be the likely cause, since having the plane break apart on its own well after takeoff is a bit of a longshot and having a surface-to-air missile doing the job is an even longer one, since the local ISIS affiliate isn't known to have that in their bag of tricks, at least not enough to reach a plane at 30K feet.
Russia doesn't want it to be a bomb, since that would point to ISIS and they'd prefer to tackle the non-ISIS factions in Syria first that are closer to the front lines of Assad-controlled territory. If this were an ISIS-inspired attack, even the autocratic Putin would have political pressure to do something coherent against ISIS as payback.
Egypt doesn't want it to be a bomb, since that makes them look bad. It would mean that the security at the Sharm el-Sheikh airport leaves a lot to be desired, since somebody snuck a bomb onboard, so security was either inept, bribed or a jihadi sympathizer (possibly all three). That is both bad news for tourism and an indication that the Egyptian military might need to do more in to fight back at the ISIS affiliate there.
Other folks aren't rooting for it not to be a bomb. If anything, having it be a bomb is in their interest, since it would make both Egypt and Russia work more against Sunni Islamists and give the Western folks trying to tamp ISIS down some help.
Russia isn't exactly friendly towards Islam and when it is, it's mostly Shia autocrats that war against both civil and jihadi flavors of Sunni folks in Syria, Yemen and Lebanon. That makes Russia an easy target, with damage to the Egyptian junta a nice piece of collateral benefit for Islamists who would be the likely bomb-placers.
Sadly, it's the Egyptian people who will take it in the neck. This will trash their tourism industry and herald a civil war in the Sinai and possibly elsewhere in Egypt. Not a good sign.